The group C adenovirus tumor antigens: identification in infected and transformed cells and a peptide map analysis

Abstract

Abstract Serum from hamsters bearing group C adenovirus-induced tumors can be divided into two classes: first, a broad spectrum serum that contains antibodies to several early adenovirus proteins, immunoprecipitated from virus-infected cell extracts, with molecular weights of 72,000, 58,000, 44,000 and 17,000 daltons; and second, a narrow spectrum serum that contains antibodies to the 58,000 dalton protein from virus-infected cell extracts. Both types of sera have been used to immunoprecipitate specifically the 58,000 dalton protein from a type 2 adenovirus-transformed hamster cell line and a type 2 adenovirus-SV40 nondefective hybrid (Ad2 + ND-1) transformed hamster cell line. In addition, the broad spectrum serum immunoprecipitates or co-precipitates a late adenovirus protein of 120,000 daltons from virus-infected, but not virus-transformed cells. Peptide maps of the 120,000 dalton antigen and the virus hexon structural protein (120,000 daltons) demonstrate that these proteins are closely related. The 72,000 dalton antigen has been shown to be the adenovirus single-strand-specific DNA binding protein. Peptide maps of this 72,000 dalton antigen demonstrate that it contains all the peptides found in the 44,000 dalton antigen. The 72,000 dalton antigen contains two additional peptide fragments not detected in the 44,000 dalton protein, indicating that this 44,000 dalton antigen is a proteolytic breakdown product of the 72,000 dalton protein. The 58,000 dalton adenovirus tumor antigen has a peptide map which is completely distinct from the 120,000, 72,000 and 44,000 dalton proteins. These data demonstrate that the 58,000 dalton antigen is chemically distinct from the 72,000–44,000 dalton early adenovirus proteins.